Metrics

Zero Runtime measures every stage of the pipeline on every turn: how long speech-to-text took, how fast the LLM produced its first token, how many tokens it used, and how quickly text-to-speech started speaking. You can read these metrics in three places:

Where	Use it to
Metrics hooks	React to a stage’s metrics in your own code, as each turn completes.
Session Dashboard	Review per-turn latency, tokens, and cost after a session.
Your observability stack	Ship metrics to Datadog, SigNoz, New Relic, or any OpenTelemetry backend.

Get metrics for each stage

Register a hook on pipeline.metrics for the stage you want. Each hook fires once per turn, when that stage finishes, and receives the stage’s metrics as a dictionary. Hooks only observe: they never change what the pipeline does, so you can register as many as you need.

import logging

from zeroruntime import Pipeline
from zeroruntime.plugins import SileroVAD
from zeroruntime.inference import TurnDetector, DeepgramSTT, GoogleLLM, CartesiaTTS

logger = logging.getLogger(__name__)

pipeline = Pipeline(
    stt=DeepgramSTT(),
    llm=GoogleLLM(),
    tts=CartesiaTTS(),
    vad=SileroVAD(),
    turn_detector=TurnDetector(),
)


@pipeline.metrics.on("stt")
def on_stt_metrics(data: dict) -> None:
    logger.info("stt %s", data)


@pipeline.metrics.on("llm")
def on_llm_metrics(data: dict) -> None:
    logger.info("llm %s", data)


@pipeline.metrics.on("tts")
def on_tts_metrics(data: dict) -> None:
    logger.info("tts %s", data)

import { Pipeline } from '@zeroruntime/js-sdk';
import { SileroVAD } from '@zeroruntime/js-sdk/plugins';
import { TurnDetector, DeepgramSTT, GoogleLLM, CartesiaTTS } from '@zeroruntime/js-sdk/inference';

const pipeline = Pipeline({
  stt: DeepgramSTT(),
  llm: GoogleLLM(),
  tts: CartesiaTTS(),
  vad: SileroVAD(),
  turn_detector: TurnDetector(),
});

pipeline.metrics.on('stt', async (data: Record<string, any>) => {
  console.log('stt', data);
});

pipeline.metrics.on('llm', async (data: Record<string, any>) => {
  console.log('llm', data);
});

pipeline.metrics.on('tts', async (data: Record<string, any>) => {
  console.log('tts', data);
});

Each stage reports its own fields. Latencies are in milliseconds.

Stage	Fires when	Fields
`stt`	Speech-to-text finishes a transcript.	`stt_latency`
`llm`	The LLM finishes its response.	`llm_ttft`, `llm_duration`, `prompt_tokens`, `completion_tokens`, `total_tokens`
`tts`	Text-to-speech finishes speaking.	`ttfb`, `tts_latency`
`eou`	The turn detector decides the user has finished speaking.	`eou_latency`, `eou_wait_ms`
`realtime`	A realtime model finishes a turn, in Realtime or Hybrid mode.	`realtime_ttfb` and input, output, text, and audio token counts
`knowledge_base`	A knowledge base search completes. Python only.	`kb_id`, `kb_retrieval_latency`, `kb_retrievals`

For every field and a complete example per stage, see Observability Hooks.

View metrics on the Dashboard

You don’t need hooks to see metrics. Zero Runtime records them for every session and shows them on the Sessions page of the Zero Runtime Dashboard. Each session lists its latency percentiles, total tokens, and total cost, and the transcript shows the latency of every turn: STT and end-of-utterance latency on user messages, TTS and end-to-end latency on agent messages.

Session List View

Sessions list showing Session ID, Room ID, created time, duration, latency, total cost, recording, and status — Sessions list on the Zero Runtime Dashboard

Session Transcript View

Session view showing session totals and latency percentiles in the header, and the transcript with timestamps, Agent and User labels, and per-message latency — Session view with the transcript, per-message latency, and recording playback

Export metrics to your observability stack

To send metrics to your own observability stack, such as Datadog, SigNoz, or New Relic, set metrics on the room’s Observability to an Exporter that points at your collector’s OpenTelemetry (OTLP) endpoint.

import zeroruntime
from zeroruntime import Exporter, Observability, Room

if __name__ == "__main__":
    zeroruntime.serve(
        MyVoiceAgent,
        room=Room(
            name="Observability Hooks",
            observability=Observability(
                metrics=Exporter(
                    enabled=True,
                    export_url="https://otel-collector.example.com/v1/metrics",
                ),
            ),
        ),
    )

import * as zeroruntime from '@zeroruntime/js-sdk';
import { Exporter, Observability, Room } from '@zeroruntime/js-sdk';

zeroruntime.serve(MyVoiceAgent, {
  room: Room({
    name: 'Observability Hooks',
    observability: Observability({
      metrics: Exporter({
        enabled: true,
        export_url: 'https://otel-collector.example.com/v1/metrics',
      }),
    }),
  }),
});

Replace the example URL with your collector’s metrics endpoint. Set the Room on serve() to apply it to every session, or on invoke() to apply it to one session.

Exporter field	Type	Default	Description
`enabled`	`bool`	`True`	Turns the metrics export on or off. Set it to `False` to stop exporting while keeping the rest of the configuration.
`export_url`	`str`	`None`	The OTLP endpoint to send metrics to. `None` uses the runtime’s default destination.
`export_headers`	`dict[str, str]`	`{}`	Headers sent with each export. Put your vendor’s API key or auth header here.

Leaving metrics unset is not the same as turning it off. An unset stream follows the runtime’s default settings. To stop exporting metrics, pass Exporter(enabled=False).

What’s Next

Logs

Set the log level and ship agent logs to your stack.

Traces

Follow each turn span by span and export the spans.

Observability Hooks

Every metrics field, with an example per stage.

References

Python
Node JS

Examples

Observability Hooks

Read per-stage metrics with pipeline hooks.

Get started

Quickstarts

Build

Testing and Eval

Observability

Deploy

Plugins

Get metrics for each stage

View metrics on the Dashboard

Session List View

Session Transcript View

Export metrics to your observability stack

What’s Next

Logs

Traces

Observability Hooks

References

Examples

Observability Hooks

Examples

Pipeline Events

​Get metrics for each stage

​View metrics on the Dashboard

​Session List View

​Session Transcript View

​Export metrics to your observability stack

​What’s Next

Logs

Traces

Observability Hooks

​References

​Examples

Observability Hooks

​Examples

Pipeline Events

Get metrics for each stage

View metrics on the Dashboard

Session List View

Session Transcript View

Export metrics to your observability stack

What’s Next

References

Examples

Examples